wastewater lineset failure

[jswin]

Got called out to look at some refrigerant lineset failures happening at wastewater building on split 410A DX, under 5Ton. Leaks at joints. Liquid and suction lines are field fabricated from copper and have turned black. Still tying to find submittal to see what they used to braze. Not a corrosion guy, but suspect hydrogen sulfide attacked.

Spec called for closed cell insulation with pvc jacket for both lines.

Here are my questions
- for those who have used copper lines in this type of environment, any suggestion on coating or other to protect from happening again.

- Anybody used an alternate material for lineset. Maybe 304L stainless? What about material for joints?

Thanks for your help

[beenthere]

Not quite the same environment. But I use blue coat on line sets in areas that have caustic vapors. Seems to hold up ok.

[genduct]

What do you think it is doing to the rest of the equipment?

Why have a 20 year lineset with 5 year equipment? Seems like paint would do the job as good as any other solution to the problem

[beenthere]

What do you think it is doing to the rest of the equipment?

Why have a 20 year lineset with 5 year equipment? Seems like paint would do the job as good as any other solution to the problem

The coils are already coated, but the line sets isn't when I get it.

[controldude]

JSWIN,
Bronze Glow is the best product I've found. I found that after the initial coating from H2S will keep the lineset from typically getting any worse but all solder joints are what really need coating with bronze Glow, H2S attacks yellow metals rapidly so if you use Staybrite you won't have as many problems but sil-phos is like making an intentional leak. I've had package units with as much as 32 leaks in the 2nd year of install since using Bronze glow on all joints (coilends, any head pressure controls, or small bulb type temp controls) all need coating off site if possible virgin copper will oxidize overnight in any headworks bldgs. Hope this long ramble helps.

[freonguy]

JSWIN:

I am at a Pulp and Paper Mill - all coils are Heresite coated, and, unfortunately all equipment comes with Silfos joints. THe H2S is the culprit to be sure - I suggest using Easy Flo 45 as there is no phosphorous in the alloy, the phosphorous is what the sulphur attacks and makes swiss cheese out of the joint.

Sta Brite works fine, in fact we have 3 remote piped Deluxe 3 Lieberts that used Sta Brite, and haven't developed a leak yet, but that is with R-22 - As for 410a, the pressures are likely beyond soft solder range of reliability. Easy Flo 45 it is, but with the flux, extra care is required to be sure.

You can buy Heresite in a can ( pricey though ) but on any repairs or new stuff using Silfos, I clean it up and give it a couple coats after the leak test / evacuation. Works for me here.

Good Luck;

Freonguy CM

[controldude]

Freonguy, Is right 45% is probably the way to go today now that everyone is going to 410A, Ijust do automation now so some other guy gets to worry about my old jobs now.

[genduct]

I was thinking H2S also but you had the real chemistry explanation. I thought the cooper would get attacked as well.

Nice post and good advice

[freonguy]

Genduct:

Yes, the copper gets attacked - but to a lesser degree.

First off, copper and brass components turn black - a thick, scaly oxide forms, especially on suction lines where there is moisture.

Secondly, there can be pin holes near the joint ( in strictly copper, no silfos ), but ( usually ) only where the copper has been heated as a function of silfos(ing ) the joint, AND, the problem seems worse if the joint was overheated originally. I suspect there is maybe a bit of granularization ( is that a word?? ) with the copper and it gives the H2S a bite on the copper, thus the leak.

I have seen as many as 5 soap bubble ' cocoons ' form adjacent to a 1/2'' silfos joint when leak checking - the best thing is to re-do the joint in 45% silver, and buff it up with a scotch pad, then hit it with a couple coats of heresite.

Freonguy CM

[CraziFuzzy]

Changing materials is good, but as mentioned, bare copper, and even stainless, will start to get eaten up after 15 years in that environment. If you want to keep those old line sets around that long, the best thing is paint. remember, painting isn't for beautification, it is a protective barrier from just these types of situations. Then insulate over the paint to keep the paint from getting damaged, and keep it dry, and you'll have sets that last 30+ years no problem.